Exchangeable guidewire

ABSTRACT

A guidewire for guiding and exchanging body insertable catheters includes a body insertable guide section and an exchange section, both formed of flexible wire. In one embodiment, a pin connector at the distal end of the exchange section includes a truncated conical head, a shank, and a groove between the head and the shank. A socket connector is attached to the proximal end of the guide section. Four indentations are formed in the socket connector, spaced apart angularly 90° from one another. The maximum diameter of the conical head is greater than the distance between opposed nodules, as the pin connector is insertable into the, it temporarily elastically deforms the socket as the head moves past the nodules. The nodules become captured within the groove, to allow rotation of the exchange section relative to the guide section while preventing any substantial axial relative movement of the sections. The exchange section can be disconnected from the guide section by withdrawing the pin connector proximally, again elastically deforming the socket as the head passes the nodules. The connectors permit repeated connections and disconnections, so the guidewire sections are reusable. In another embodiment, the pin connector has a cylindrical head and a narrower recess adjacent the head, and an indentation is formed in the socket connector with a gradually inclined wall that terminates in a steeply inclined edge.

BACKGROUND OF THE INVENTION

The present invention relates to devices employed in catheter guidingand exchanging procedures, and more particularly to guidewire andexchange wire interconnection apparatus.

Catheterization procedures, e.g. percutaneous transluminal angioplastycatheterization (PCTA), involve insertion of catheters into bloodvessels and other body passageways. Frequently such passageways areconvoluted, giving rise to difficulties in inserting the catheters.Accordingly, guidewires are employed to insure accurate positioning ofbody-inserted catheters.

More particularly, a guidewire is inserted and maneuvered along arterialor other passageways to the desired treatment site, leaving a proximalportion of the guidewire outside of the patient. Next, the catheter isthreaded onto the guidewire proximal portion, which is received into alumen formed in the catheter. The catheter is advanced over theguidewire, and thus guided to the desired treatment site. Typically theguidewire is at least slightly longer than the catheter, so that whenthe catheter is completely advanced to the treatment site, at least partof the guidewire proximal end portion protrudes from the catheter. Forexample, for a catheter length of 130 centimeters, the guidewire lengthcan be about 150 centimeters.

Frequently in catheterization, the need arises to exchange catheters.Preferably the exchange is accomplished with the guidewire remaining inplace, to avoid the need to maneuver yet another guidewire to thetreatment site. An exchange requires gripping the guidewire proximal endportion to maintain its position while the catheter is removed in theproximal direction. However, well before the originally insertedcatheter can be withdrawn in this manner, it completely covers theguidewire, and the physician or other user can not simultaneouslymaintain the guidewire and proximally move the catheter.

In view of this difficulty, the usual approach has been to remove theguidewire from the patient, leaving the originally inserted catheter inplace to guide the advancement of an exchange wire to the treatmentsite. The exchange wire is substantially longer than the guidewire. Theproximal portion of the exchange wire, remaining outside of the patientafter complete insertion, is longer than the length of the catheter.Thus, the exchange wire can be maintained while the catheter iscompletely withdrawn from the patient. After a replacement catheter isinserted over the exchange wire, the exchange wire is removed and theguidewire reinserted.

The repeated advancing and withdrawing of guidewires and exchange wirespresents undue risk of trauma to the blood vessels or other lumens, andincreases the complexity and required time for the catheterizationprocedure.

Several guidewire and exchange wire coupling schemes have been proposedto avoid the need for the wire exchanges. For example, U.S. Pat. No.4,917,103 (Gambale et al) and U.S. Pat. No. 4,922,923 (Gambale et al)disclose a guidewire and exchange wire interconnection system. A hollowtubular fitting is provided at the proximal end of the guidewire, whilea reduced diameter tip is formed at the distal end of the exchange wire.With the distal tip inserted into the tube, the tube is crimped to forma permanent coupling of the wires.

U.S. Pat. No. 4,966,163 (Kraus et al) shows an extendable guidewireincluding a main section and an extension section. A releasable couplingof these sections is provided by an externally threaded male contact atthe proximal end of the main section, and an internally threaded femalecontact at the distal end of the extension section. The female contactis mounted to rotate relative to the extension section.

Yet another coupling scheme is disclosed in U.S. Pat. No. 4,827,941(Taylor et al). A guidewire assembly includes a main section with areduced diameter undulating (sinusoidal) male contact at its proximalend. An extension section includes a tube at its distal end. Thesinusoidal contact elastically deforms as it is inserted into the tube,to provide a friction fit. A similar approach is shown in U.S. Pat. No.4,958,642 (Christian et al). Another friction fit approach is disclosedin U.S. Pat. No. 4,875,489 (Messner et al). A main section of anextendable guidewire has a tapered proximal end. An auxiliary section ofthe guidewire has a tube at its distal end. The tube has a longitudinalgap, and thus expands to receive the tapered end of the main section andresiliently retain the tapered end once inserted.

While the above approaches perhaps are an improvement as compared tomultiple wire exchanges, each encounters difficulties, particularly inconnection with smaller guidewires and exchange wires, which can havediameters as low as ten one-thousandths of an inch.

Therefore, it is an object of the present invention to provide a singledevice for performing the functions of the guidewire and the exchangewire in catheterization procedures.

Another object of the invention is to provide a simple and reliablemeans for releasably coupling a guidewire and an exchange sectionproximal to the guidewire.

A further object is to provide a guidewire/exchange wire system withseparate guide and exchange sections releasably coupled to one anotherin a manner that prevents the transfer of torque from one section to theother.

Yet another object is to provide a guidewire with complementary contactsfor coupling an exchange section to a guide section of the guidewire, ina manner that affords a tactile sense of completing the connection.

SUMMARY OF THE INVENTION

To achieve these and other objects, there is provided an interconnectionapparatus for body insertable guidewires and exchange wires. Theapparatus includes a first connector fixed to one end of a first wire.The first connector is substantially symmetrical about a first connectoraxis and has first and second axially opposite end regions. A groove isformed in the first connector between the end regions. A secondconnector, fixed to one end of a second wire, has a second connectoraxis and a projection means. The first and second connectors arepositionable in confronting and axially aligned relation, for axialmovement of the connectors relative to one another toward a mechanicalcoupling. When the connectors are mechanically coupled, the projectionmeans extends radially into the groove. At least one of the connectorsis elastically deformable to allow passage of the projection meansaxially inward past one of the end regions and into the groove as theconnectors are moved axially relative to one another. Once theprojection means has passed that end region and resides within thegroove, the end regions tend to confine the projection means within thegroove to prevent any substantial axial movement of the connectorsrelative to one another away from the mechanical coupling.

Preferably the first and second connectors, when mechanically coupled,are rotatable relative to one another about the first connector axis.This prevents the transfer of torque from one of the wires to the other,and thus reduces or eliminates torsional stress that otherwise can leadto kinking or damage, particularly for wire sections of small diameter,e.g. ten mils.

To achieve a releasable coupling, the flexible connector further iselastically deformable to allow axially outward passage of theprojection means away from the groove and past the first end region ofthe first connector, thus to disengage the first and second wires.

In one preferred version of the interconnection apparatus, the first endregion is a truncated cone that diverges in the axial direction towardthe groove, and the second end region is a shank on the opposite side ofthe groove from the cone. The outside diameter of the shank and themaximum outside diameter of the truncated cone are substantially equal,both being greater than the outside diameter of the groove. Thecomplementary second connector is a socket having an annular wall, withthe projection means comprising four indentations formed in the annularwall along a medial region of the socket. The indentations are angularlyspaced apart from one another by 90°, to form two pairs of opposeddimples or nodules at the medial region of the socket. The diameter ofthe truncated cone and shank is greater than the distance between eachpair of nodules. Consequently the socket yields along its medial regionto allow passage of the truncated cone, to position the nodules withinthe groove. Once the truncated cone is past the nodules, they arecaptured within the groove. The truncated cone and shank cooperate tomaintain the nodules in the groove, and thereby maintain the mechanicalcoupling of the connectors.

The outside diameter of the groove can be selected with reference to thedistance between opposed nodules, to permit a substantially freerotation of the socket relative to the first connector. This preventsany substantial transmission of torque from one of the wires to theother.

In practice, the first connector (a distal pin) is formed into theexchange wire at its distal end, with the socket fixed to the proximalend of the guidewire. With the guidewire inserted into the patient andwith its distal tip at the treatment site, the proximal end portion ofthe guidewire, including the socket, remains outside of the patient. Theexchange section of wire is coupled to the guidewire by sliding thefirst connector distally into the socket, until the projecting nodulesand groove are axially aligned.

As mentioned, some elastic deformation of the socket is required topermit the projections to clear the truncated cone. Clearance of thecone leads to at least partial return of the socket to its normal,unstressed configuration, which gives the user a tactile sensation ofthe mechanical coupling.

Thus, the combination of the pin connector and socket connector providefor a reliable, releasable, and repeatable mechanical coupling ofguidewire and exchange sections. The coupling is achieved by simplerelative sliding of the pin connector and socket connector, and entry ofthe protrusions into the groove signals a physician or other user thatthe coupling is accomplished. The same type of motion, i.e. relativesliding of the connectors, disengages the mechanical coupling. Thus,connecting and disconnecting the wire sections demands relatively littleattention on the part of the physician, who then is able to devote mostof his or her attention to the catheterization procedure at hand.

IN THE DRAWINGS

For a further understanding of the above and other features andadvantages, reference is made to the following detailed description andto the drawings, in which:

FIG. 1 is a side elevation of a guidewire assembly including connectedguide and exchange sections constructed in accordance with the presentinvention;

FIG. 2 is an enlarged side elevation of a distal end region of theexchange section;

FIG. 3 is an enlarged side elevation of a proximal end region of theguide section;

FIG. 4 is a proximal end view of the guide section;

FIG. 5 is a sectional view taken along the line 5--5 in FIG. 4, with asocket connector of the guide section shown removed from the remainderof the guide section;

FIG. 6 is a sectional view taken along the line 6--6 in FIG. 5;

FIGS. 7-9 are diagrammatic views illustrating progressive insertion of apin connector of the exchange section into the socket;

FIG. 10 is an end view of an alternative embodiment socket connector;and

FIGS. 11-15 illustrate an alternative embodiment guidewire including pinand socket connectors.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Turning now to the drawings, there is shown in FIG. 1 an exchangeableguidewire 16. The guidewire includes two releasably coupled sections: aguide section 18 and an exchange section 20. Sections 18 and 20preferably are constructed of stainless steel, for example a type ofsteel known as "No. 304" stainless steel, each being approximately 150centimeters in length. Guide section 18 and exchange section 20 have thesame diameter, which preferably is in the range of from about 0.010inches to about 0.060 inches. Guide section 18 has a distally convergingdistal tip 22, and a socket connector or sleeve 24 at its proximal end.Exchange section 20 has a proximal end and a distal end removablyinserted into socket 24.

The distal end region of exchange section 20 is shown in FIG. 2. Aportion of the stainless steel wire at the distal end is selectivelyremoved, to form a pin connector 28. More particularly, material isremoved by a precision grinding of the exchange section by relativerotation of the exchange section and a grinding tool (not shown) about acentral longitudinal axis 30 of the exchange section. As a result, pinconnector 28 is concentric on axis 30, and transverse profiles, i.e.profiles taken perpendicular to axis 30 along the connector, arecircular.

Pin connector 28 has a distal tip or head 32 in the form of a truncatedcone, diverging in the proximal direction from a blunt distal end 34 toa maximum cone diameter at 36. This divergence is gradual, in the sensethat the angle between the inclined cone surface 38 and axis 30 is lessthan 45°, and more preferably about 20°. Connector 28 further includes aproximal shank 40, having an outside diameter substantially equal to themaximum diameter of cone 32. Between shank 40 and the remainder ofexchange section 20 is an inclined surface 42.

Pin connector 28 further includes an annular recess or groove 44, formedalong an intermediate region of the connector between shank 40 and cone32. Over most of its length, groove 44 has an annular surface 46concentric on axis 30. On opposite sides of surface 46 are inclinedgroove surfaces 48 and 50 near the shank and cone, respectively.Surfaces 48 and 50 are steeply inclined, in the sense that the angle ofeach surface with respect to axis 30 is at least 45°.

FIG. 3 shows the proximal end region of guide section 18, includingsocket connector 24 and a proximal end of the wire forming the guidesection. Socket connector 24, over most of its length, has an annularwall in the form of a hollow, circular cylinder. However, at its medialregion 54, socket connector 24 is formed to provide four indentationsprojected inwardly toward a longitudinal central axis 56 of the socketconnector. These indentations provide nodules or dimples, formedangularly spaced apart from one another at 90° intervals. Thus, thereare two opposed pairs of the nodules, one including nodules 58 and 60,and the other pair including nodules 62 and 64 (FIG. 4).

As perhaps best seen in FIG. 5, the distance "a" between the pair ofindentations 58 and 60 is less than the nominal inside diameter "b" ofsocket connector 24 over the majority of its length. The same is truefor the distance between indentations 62 and 64. At the distal end ofthe socket connector is an annular beveled surface 66.

Further in FIG. 5, the proximal end of the guide section is withdrawnfrom the socket connector to reveal a proximal extension 68 having anoutside diameter approximately equal to but slightly less than insidediameter "b" of the socket connector. Between extension 68 and theremainder of guide section 18 is an annular beveled transition surface70. Socket connector 24 is permanently secured to guide section 18, byan interference fit of extension 68 within socket connector 24, withparallel beveled surfaces 66 and 70 contiguous. Preferably an adhesiveis applied to at least one of surfaces 66 and 70 before the socketconnector and guide section are engaged, in which case the adhesivefurther secures the connection.

The maximum cone diameter and the shank outer diameter, indicatedrespectively at "c" and "d" in FIG. 2, are approximately equal to oneanother, greater than distance "a" between indentations 58-64, and lessthan inside diameter "b" of socket connector 24. An outside diameter ofgroove 44, indicated at "e" in FIG. 2, likewise is less than diameters"c" and "d" and preferably is about equal to distance "a".

Pin connector 28 and socket connector 24 provide for a releasablemechanical coupling of the exchange and guide sections, in which thesocket connector surrounds the pin connector, indentations 58, 60, 62and 64 are aligned with and captured within groove 44, and axes 30 and56 substantially coincide. The joinder of connectors 24 and 28 isillustrated in FIGS. 7-9. As seen in FIG. 7, conical head 32 of the pinconnector is inserted into the proximal end of socket connector 24, thenmoved distally toward indentations 58-62. This insertion is facilitatedby the fact that the cone diameter, near distal end 34, is substantiallyless than the distance "a" between opposed indentations, and thus issubstantially less than the interior diameter "b" of the socketconnector.

As pin connector 28 is moved rightward as viewed in FIGS. 7-9, cone 32eventually encounters the indentations. Further rightward movement ofthe cone elastically deforms socket connector 24 particularly alongmedial region 54. Thus, surface 38 of cone 32 functions as a cam,forcing indentations 58-64 apart from one another against the elasticrestoring force of the socket, until the maximum diameter portion of thecone is axially aligned with the indentations, as viewed in FIG. 8. Thegradual (20°) incline of cone surface 38 facilitates insertion ofconnector 28. More particularly, due to the gradual incline, therequired axial insertion force is relatively small as compared to theradial force required to elastically deform the socket connector.

When pin connector 28 is inserted beyond the position illustrated inFIG. 8, indentations 58-64 move radially inward due to the elasticrestoring force of the socket, into an engagement with groove surface46. This movement is relatively rapid, due to the steep incline ofgroove surface 50 and the restoring force. The rapid movement andengagement provide a tactile sensation to the physician or other userattempting to connect the extension and guide sections, that amechanical coupling has been achieved.

As shown in FIG. 9, when connectors 24 and 28 are coupled, indentations58-64 are axially aligned with and captured within groove 44. Therelatively steep incline of beveled surface 50 insures that a proximalremoval of pin connector 28 requires a substantially greater axial forceas compared to connector insertion. The steep incline of beveled surface48 likewise resists distal insertion of pin connector 28 beyond thedesired axial alignment.

Accordingly, the mechanical coupling does not depend upon a frictionalengagement of the nodules or indentations against the groove surface.There is no need for an elastic restoring force to maintain the nodulesagainst the groove surface. In fact, in the preferred mechanicalcoupling, the distance "a" between indentations is approximately equalto the groove diameter "e", so that pin connector 28, when mechanicallycoupled within socket connector 24, remains free to rotate relative tothe socket about connector axes 30 and 56. Consequently, exchangesection 20 is maintained axially relative to guide section 18 whencoupled, yet is free to rotate relative to the guide section. Thisarrangement prevents any substantial transfer of torque from theexchange section to the guide section, and thus substantially eliminatesthe chance for twisting, kinking, and other damage to the wires formingthe guide and exchange sections. This advantage is increasingly criticalfor wire sections having small diameters, i.e. at or approaching 0.010inch.

As previously mentioned, the mechanical coupling of connectors 24 and 28is releasable. More particularly, exchange section 20 is pulledproximally relative to the guide section, whereby inclined surface 50 ofthe groove acts as a cam to deform the socket connector and thereby movethe indentations radially outward and apart from one another. While therequired axial force for disconnecting the extension section is greaterthan the insertion force in joining the sections, disconnectionnonetheless is conveniently accomplished manually, with one handgripping each of the extension and guide sections. Regardless of whetherpin connector 28 is being inserted or removed, the requisite deformationof socket connector 24 is elastic, which allows for repeated connectionsand disconnections as required during the medical procedure, withoutreducing the efficacy of the mechanical coupling.

The use of guidewire 16 can be considered in connection with anangioplasty procedure to treat a blood vessel occlusion, formed forexample due to an accumulation of plaque. This exemplary procedureinvolves two dilatation steps, followed by placement of a prosthesis.

The procedure is initiated by percutaneous and intravascular insertionof guide section 18, to a point where distal tip 22 is aligned with theocclusion site. At this stage, guide section 18 is free of exchangesection 20. Nonetheless, guide section 18 is sufficiently long (e.g. 150centimeters) such that with distal tip 22 so aligned, a proximal portionof the guide section including socket connector 24 remains outside ofthe patient.

Next, an initial dilatation catheter (not shown) is inserted, by placingits distal end over proximal end 52 of guide section 18. A lumen in thedilatation catheter accepts the guide section. The dilatation catheteris progressively advanced until a balloon at the distal end of adilatation catheter is aligned with the occlusion. With guide section 18in place, the dilatation catheter is positively directed toward thetreatment site, and thus can be inserted relatively quickly withoutrequiring undue attention. A proximal portion of the dilatation catheterremains outside of the patient, and the proximal portion of the guidesection extends at least a slight distance proximally of the dilatationcatheter. At this stage, the dilatation balloon is expanded to enlargethe vessel at the treatment site.

After the initial expansion of the vessel at the occlusion, thedilatation catheter is withdrawn. The conventional procedure involvedremoving a guidewire and inserting a much longer exchange wire. Inaccordance with the present invention, guide section 18 remains inplace, while exchange section 20 is coupled to the guide section byinserting pin connector 28 into socket connector 24, while holding thesocket connector in place to maintain the axial position of guidesection 18. A simple and direct axial (distal) pushing of the pinconnector is all that is required. The socket connector is elasticallydeformed temporarily, then rapidly returns to its normal configurationas groove 44 becomes aligned with indentations 58-64. This return of thesocket connector brings the indentations against groove surface 46,providing a "snap fit" sensation that positively informs the physicianwith a tactile sensation of a successful coupling.

Several advantages arise from the fact that socket connector 24, whencoupled, is in a relaxed state, rather than elastically deformed. First,there is no risk that gradually diminishing elastic restoring forcemight degrade the connection. Secondly, no torque is transferred throughthe interconnection. Accordingly, exchange section 20 can be rotated(whether intentionally or inadvertently) without rotating the proximalend of the guide section. Thus the exchange section can be manipulatedas necessary, without the risk of twisting or kinking along the guidesection.

Returning to the procedure, the coupling of guide section 18 andexchange section 20 substantially increases the length of wire outsideof the patient (e.g. by another 150 centimeters). Exchange section 20can be gripped by hand to maintain the axial position of guide section18 while the initial dilatation catheter is proximally withdrawn.

After withdrawal, the guide and exchange sections remain coupled, as asecond dilatation catheter (not shown) is inserted. More particularly,the second dilatation catheter has a lumen that accepts proximal end 26of exchange section 20, enabling progressive advancement of thedilatation catheter along the guidewire until the second (perhapslarger) dilatation balloon is aligned at the treatment site. At thisstage, connectors 24 and 28 are proximal of the second dilatationcatheter, and it is advantageous to disconnect and remove the exchangesection. Disconnection is accomplished easily by hand, holding socketconnector 24 in place while proximally pulling the exchange section nearpin connector 28. Disconnection requires temporary elastic deformationof socket connector 24. Disconnection is easily accomplished by hand.With the exchange section removed, there is no need for an attendant tohandle an unwieldy length of exchange wire, and the physician canconcentrate on the angioplasty procedure at hand, without distractiondue to the exchange wire, as the second dilatation balloon is expandedagainst the occlusion.

After the second dilatation step, exchange section 20 is again coupledto guide section 18 as described above, and the second dilatationcatheter is withdrawn over the guide and exchange sections. With thesections remaining coupled, a prosthesis delivery catheter is insertedover the proximal end of the exchange section, and advancedprogressively until a prosthesis (e.g. a radially self-expanding stent)at the distal end of the catheter is aligned at the treatment site. Atthis point the exchange section is disconnected and removed, leavingjust the proximal portion of the guide section exposed beyond theprosthesis delivery catheter. The physician can concentrate onprosthesis deployment and delivery, free of concern about exchangesection 20.

Following prosthesis deployment, guide section 18 and the deploymentcatheter are withdrawn. Alternatively, should any further catheters berequired (e.g. an endoscopic catheter to view stent placement), theguide and exchange sections are coupled once again to enable withdrawalof the delivery catheter while guide section 18 remains in place. Ineither event, repeated connections and disconnections of the guide andexchange sections do not structurally alter either connector, or in anyother manner degrade the quality of the mechanical coupling.

FIG. 10 shows a socket connector 72 utilized in an alternative guidewiresystem, in which the exchange section is similar to exchange section 20.Three indentations 74, 76 and 78 are formed in the annular wall ofsocket 72 at its medial region, with the indentations spaced apart fromone another angularly by about 120°. Insertion of the exchange sectioninto socket 72 forces indentations 74-78 radially outward away from oneanother, much in the manner as described above in connection with socketconnector 24. Again, mechanical coupling involves an axial alignment ofthe indentations with a groove in the tip connector, with theindentations captured within the groove.

FIGS. 11-15 illustrate another highly preferred embodiment guidewire 80,including a guide section 82 and an exchange section 84, coupledrelative to one another by a socket connector 86. More particularly, apin connector 88 at the proximal end of the guide section, and a pinconnector 90 at the distal end of the exchange section, are insertedinto socket connector 86, to be retained within the socket connector asshown in broken lines.

FIG. 12 shows pin connector 90 in greater detail. A truncated conicalregion 92 converges distally from the nominal diameter of the exchangesection to a shank 94 of the pin connector. An annular recess or groove96 is formed in the pin connector, near a cylindrical head 98 that formsthe distal end of the pin connector. A steeply inclined groove surface100 is disposed between the groove and the head. Between the groove andshank 94 is a more gradually inclined groove surface 102.

Pin connector 88 of the guide section is substantially identical to pinconnector 90.

Socket connector 86 is shown in greater detail in FIGS. 13 and 14. Thesocket includes an annular wall 103 with opposite proximal and distalends 104 and 106 for insertion of pin connectors 90 and 88,respectively. Connector wall 103 is selectively cut and crimped to forma proximal indentation 108 and a distal indentation 110, facing inopposite directions but otherwise substantially identical to oneanother. In each case, a transverse slit through connector wall 103permits a controlled bending or crimping of a selected area of connectorwall 103 on one side of the slit.

As seen in connection with proximal indentation 108 (FIG. 14), theresult of this selective reshaping is a gradually inclined wall portion112 having an arcuate lateral profile terminating in a relatively steepdistal edge 114. Wall portion 112 is visible in FIG. 14 through anopening 115 between edge 114 and connector wall 103, which opening isformed as a result of the slit and selective reshaping.

Distal indentation 110 is substantially identical to indentation 108,having a gradually inclined wall portion 116 that terminates at asteeply inclined edge 118 (FIG. 13).

FIG. 15 schematically represents the insertion of pin connector 90 intosocket connector 86. The diameter of head 98, indicated at "c", is lessthan the inside diameter "b" of the socket connector, but exceeds thedistance "a" between proximal indentation 108 and the opposite side ofwall 103. Thus, as pin connector 90 is moved rightward as viewed in thefigure, head 98 eventually contacts wall portion 112 of indentation 108.Upon further rightward movement of the pin connector, head 90elastically deforms socket connector 86, particularly in the region ofindentation 108. As head 98 moves rightwardly along gradually inclinedsurface 112, the socket connector is deformed a sufficient amount topermit passage of the head rightwardly beyond indentation 108, to alignthe indentation with groove 96. The gradual incline of wall portion 112facilitates insertion of pin connector 90, much in the same manner thatpreviously discussed cone surface 38 promotes insertion of pin connector28.

Once head 98 is beyond indentation 108, socket connector 86 elasticallyrecovers, i.e. returns to the shape of its relaxed condition, whereinthe indentation and opposite portion of connector wall 103 are onceagain separated by the distance "a". Elastic recovery is relativelyrapid, due to the steep incline of groove surface 100 and the elasticrestoring force in the socket connector. Thus, as before, elasticrecovery provides a tactile sensation that a mechanical coupling hasbeen achieved. The relatively steep incline of groove surface 100, andthe relatively steep incline of edge 114, insure that a proximal removalof pin connector 90 requires substantially greater axial force thanconnector insertion.

Preferably, the distance "a" slightly exceeds the diameter "d" of groove96, so that when mechanically coupled, pin connector 90 and socketconnector 86 nonetheless remain free to rotate relative to one another,thus to allow exchange section 84 to rotate relative to guide section 82while being maintained axially relative to the guide section. Aspreviously noted, this feature prevents any substantial transfer oftorque from the exchange section to the guide section.

Pin connector 90 includes a gradually inclined groove surface 102proximally of groove 96, as opposed to the relatively steep surface 48of pin connector 28. Surface 102 is not relied upon to limit the distalmovement of pin connector 90 relative to socket connector 86. Rather,such distal movement is limited by conical region 92 of pin connector,as this surface encounters proximal end 104 of the socket connector.

Insertion of pin connector 88 into socket connector 86 is accomplishedin much the same manner as insertion of pin connector 90, except thatpin connector 88 is inserted into distal end 106 and moved in theproximal direction to the point of mechanical connection.

Thus, proximal indentation 108 and distal indentation 110 capture head98 and a head 120 of pin connector 88, respectively, which maintains themechanical coupling of the pin connectors within socket connector 86.Further, however, it is preferred to permanently bond the socketconnector to pin connector 88 and guide section 82. This is accomplishedby joining an inclined surface 122 of connector 88 to a similarlyinclined surface at distal end 106 of the socket connector, afterapplying a suitable medical adhesive to one or both of these surfaces.

Socket connector 86 and pin connectors 88/90 afford several advantagesover socket connector 24 and pin connector 28. Indentations 108/110, ascompared to nodules 58-64, are easier to form, and can be formed withmore consistency (tighter dimensional tolerances) over numerousrepetitions. More importantly, however, is that indentations 108/110 canbe formed asymmetrically, to provide the gradual wall portion incombination with the steep edge. The result, as noted above, is tofacilitate insertion of the pin connectors while providing substantiallyincreased resistance to their withdrawal, without the need for specialshaping of the connector tip, e.g. as in providing conical head 32 ofpin connector 28. The conical head is difficult to form, particularlyfor small diameter guidewires. Accordingly, elimination of the need tofabricate the cone is a substantial advantage.

Typical guidewires in accordance with the present invention can havediameters ranging from about 0.014" to 0.018" for coronary applications,and from about 0.018" to 0.063" for peripheral applications. In onepreferred version of guidewire 80, the wire, pin connector and socketconnector dimensions in inches are as follows:

Pin Connectors:

Wire outside diameter: 0.014

Shank outside diameter: 0.009

Groove outside diameter: 0.007

Head outside diameter: 0.009

Socket Connector:

Length: 0.75

Nominal inside diameter: 0.010

Distance between indentations and opposite side of socket: 1.00

Guidewire:

Outside diameter: 0.014

Thus in accordance with the present invention, catheters can beexchanged repeatedly while a distal guide section remains in place forguiding each catheter to the treatment site. An exchange section iseasily and quickly connected to the guide section to provide an extendedproximal region of the guidewire when needed for catheter insertion orwithdrawal. When no longer needed, the exchange section is easilydisconnected. Because each connection and disconnection requires only atemporary elastic deformation of the connector structure, repeatedconnections and disconnections do not degrade the quality of thecoupling. There is no substantial elastic load during coupling, furtherinsuring against degradation and preventing the transfer of torque fromthe exchange section to the guide section. Finally, the manner in whichthe nodules of one of the connectors are captured into a groove of theother connector, provides a tactile sensation to signal the physician ofa successful coupling.

What is claimed is:
 1. An interconnection apparatus for body insertableguidewires and exchange wires, including:a first connector at one end ofa first wire, said first connector being substantially symmetrical abouta first connector axis and having a first end region and a recessedregion adjacent the first end region; and a second connector adapted formounting at one end of a second wire, said second connector having asecond connector axis and a projection means; wherein the first andsecond connectors, when positioned in confronting and at least generallyaxially aligned relation, are movable axially toward one another into amechanical coupling in which the projection means is aligned with andextends radially toward the recessed region; a selected one of theconnectors elastically deforming to allow the first end region to travelaxially inward past the projection means as the connectors are movedtoward said mechanical coupling and further at least substantiallyelastically recovering upon movement of the connectors into saidmechanical coupling; the projection means and the first end region, withthe connectors in said mechanical coupling, engaging one another tolimit axial movement of the connectors away from one another to maintainthe mechanical coupling; and wherein the first and second connectors arerotatable relative to one another when in said mechanical coupling; andwherein the second connector comprises a socket having an annular wall,and the first connector is inserted into the socket and surrounded bythe socket when in said mechanical coupling; and the projection meanscomprises at least one indentation formed in the annular wall along amedial region of the socket.
 2. The apparatus of claim 1 wherein:theprojection means comprises a plurality of indentations formed along themedial region and equally angularly spaced apart from one another. 3.The apparatus of claim 2 wherein:the projection means comprises four ofthe indentations angularly spaced apart from one another 90° to providetwo pairs of opposed indentations at the medial region of the socket,wherein a distance between each pair of opposed indentations is lessthan a nominal interior diameter of the socket.
 4. The apparatus ofclaim 3 wherein:an outer diameter of the first end region of the firstconnector is less than the nominal interior diameter of the socket andgreater than the distance between each pair of opposed indentations, andwherein the socket is elastically deformable to permit insertion of thefirst connector into the socket to carry the first end region past theindentations, to axially align the indentations and the groove.
 5. Theapparatus of claim 1 wherein:an outer diameter of the second end regionof the first connector is less than the nominal interior diameter of thesocket and exceeds the distance between each pair of opposedindentations.
 6. The apparatus of claim 5 wherein:the distance betweeneach pair of opposed indentations is at least equal to an outer diameterof the groove, whereby the first connector, when in the mechanicalcoupling, is free to rotate relative to the socket about the firstconnector axis.
 7. An interconnection apparatus for body insertableguidewires and exchange wires, including:a first connector at one end ofa first wire and having a first end region and a first recessed regionadjacent the first end region; a second connector at one end of a secondwire and having a second end region and a second recessed regionadjacent the second end region; an elongate third connector having firstand second opposite ends for receiving the first and second connectors,respectively, and further having a first projection means between thefirst and second ends; wherein the first and second connectors, whenpositioned in confronting relation to the third connector at the firstand second ends, respectively, are movable axially toward one anotherand relative to the third connector into a mechanical coupling in whichthe first projection means is aligned with and projects radially towardthe first recessed region; a selected one of the first and thirdconnectors elastically deforming to allow the first end region to travelaxially inward past the projection means as the connectors are movedtoward said mechanical coupling and further at least substantiallyelastically recovering upon achievement of said mechanical coupling,whereupon the first end region and the first projection means arepositioned to engage one another to limit axial movement of the firstconnector and third connector away from one another to maintain themechanical coupling; and a means for joining the second and thirdconnectors to one another.
 8. The apparatus of claim 7 wherein:saidmeans for joining the second and third connectors to each other comprisean adhesive for bonding said second end of the third connector to thesecond connector.
 9. The apparatus of claim 7 wherein:said means forjoining the second and third connectors comprises a second projectionmeans in the third connector and axially spaced apart from the firstprojection means and, upon insertion of the second connector asufficient distance to move the second end region beyond the secondprojection means, positioned to engage the second end region to limitaxial movement of the second connector and third connector axially awayfrom one another.
 10. The apparatus of claim 9 wherein:the first andsecond projection means respectively comprise first and secondindentations, each indentation including a gradually inclined wallportion terminating in a steeply inclined edge, and wherein each of thefirst and second connectors, when being inserted into the thirdconnector toward its associated indentations, encounters the graduallyinclined wall portion before encountering the steeply inclined edge.